Structural features of a Eu³⁺ doped nuclear glass and gels obtained from glass leaching

In order to describe the rare earth environment in an aluminoborosilicate nuclear glass and its evolution with water leaching, Eu³⁺ was used as a luminescent structural probe. Two types of Eu³⁺ environments were observed in the glass as well as in the gels (originating from leached glass). A study of the B₂ crystal field parameters allows one to identify one site as a silicate type. We showed moreover that the second site is modified with leaching from a borate to an aluminate site. Asymmetry ratio from photoluminescence and Mössbauer analyses demonstrated a decrease of the average distortion of the Eu³⁺ sites in the gels. Indeed, gel can be described as an amorphous matrix but less disordered than glass. Another important result is that the lanthanide environment is not influenced by the leaching mode.